An increase in vasoactive intestinal peptide levels in canine endotoxin shock

Some of the many metabolic and cardiovascular activities and effects of vasoactive intestinal peptide are quite similar to the changes observed in endotoxin shock. The changes occurring in plasma vasoactive intestinal peptide levels during canine endotoxin shock were studied. Vasoactive intestinal peptide levels were markedly and significantly elevated following the administration of endotoxin, corresponding well with the drop in systemic blood pressure. In the dogs surviving the experiment, plasma vasoactive intestinal peptide levels returned to normal levels after 24 hours, corresponding well with the restoration of normal hemodynamic values. Surviving dogs exhibited significantly lower vasoactive intestinal peptide levels than did nonsurvivors. Many of the biologic activities of vasoactive intestinal peptide make it suitable for counteracting endotoxemia, thus acting as the defense of the body against endotoxin. However, the lower vasoactive intestinal peptide levels in the surviving dogs rather points to vasoactive intestinal peptide as a causative factor in canine endotoxemia.